Presently, there are no commercial devices, which directly can be used in applications for controlling a number of devices in one or several spaces and specially allow a central control over a backbone control bus.
The available programmable units, e.g. for distributed I/O via a PLC, must be provided with additional fuses for each individual group and output circuit breakers to manage the consumer load. Moreover, these solutions require profound knowledge from the system architectures.
When controlling, for example analogues or serial signals, usually specially adapted devices are used. The information representation is normally limited since only few instruments can be coupled to the same signal. If additional signals are required, signal converters, amplifiers, etc. must be employed. If a signal must be scaled, more expensive apparatuses are needed.
The traditional installations use separate switching and fusing. Using distributed I/O units with output circuit breakers demands much more installation work, which consequently increases the interest of employing this technique. Moreover, the cost of the system usually makes it unbeneficial for small applications, which results in limited systems.
In applications where the output current is monitored, for example when the condition of a light bulb or the like is checked, usually a simple monitoring of an active output and keeping the current within a predetermined level is performed. If the light is on, then it will consume a specific amount of current, and if the current level is not correct then the light bulb is defected.
In applications, in which detector outputs are monitored in different points special dedicated detectors are arranged. It is also possible to read analogue/serial signals in a number of points without using signal converters or amplifiers. In addition, it is possible to convert the signals to adapt the measurement result from, for example a non-analogues detector to the used apparatuses. However, the adjustment for scaling with the aim of obtaining minimum/maximum values from a detector and displaying the minimum/maximum value on an instrument is usually eliminated. As an alternative, a non-liner instrument can be provided to compensate the incorrect signal received from a non-linear sensor.
FIG. 1 shows an embodiment according to the known technique. The system 10 comprises a number of central units 11 arranged in compartments 12a–12n. To each central unit 11 a power supply line 13 is connected. Each central unit 11 is connected to a switching arrangement 14 and supplies the devices (not shown) connected to each switching arrangement with power, preferably down (or up) transformed current/voltage. Each switching arrangement is connected to a controller unit 15, such as a Programmable Logic Controller (PLC). The PLC 15 controls the switching arrangement by sending control signals to the same, which connects or breaks the circuit including the controlled devices. Each PLC receives inputs from the controlled devices or other detectors, based on which input signals the devices can be controlled. The PLCs are controlled and programmed through a computer (PC) 16.
Other techniques are known. In U.S. Pat. No. 5,941,966, for example, a transmitter end stage for a data transmission system comprising at least one control unit and data transmission lines, especially for a CAN bus system having at least one CAN controller and one CAN bus (CB) is proposed, characterized by the fact that the individual circuit elements of transmitter end stage are integrated monolithically. As a result of the special layout and its circuit-design arrangement of the individual elements of the transmitter end stage, the effects of malfunctions, for example of short circuits of the data lines to ground or to the supply voltages, are reduced to a minimum.
As a result of the special choice of pre-drivers, minimum delay times are achieved, so that signals can be transmitted at a higher data rate.
WO 99/14643 discloses a loom control system in which a CAN bus, or other bus system, is extended by a daisy chain. After the loom has been switched on, or after a number of machine conditions, there is an initial automatic configuration of the internal and external units for the bus, and then the start is released for the daisy chain to be used for the configuration and, selectively, also as a trigger line. Fixed addresses are established for the operation of the units with the same function or to be bought in. The units with the same function have a group address for a multiple function, and each unit is assigned an additional number.
The international application no. WO 94/24618 relates to a centralized control logic device for a plurality of elements to be controlled. The device comprises a central controller having two input/output lines for transmitting and receiving data messages comprising an address, a control input means, a plurality of repeaters having first and second input/output terminals and by-pass input/output means. The repeaters are connected in series and form a ring control circuit with both ends connected to respective input/output lines and controllable automatic addressing units connecting by-pass input/output means to the elements to be controlled. The device may be used for controlling the various components.
In U.S. Pat. No. 5,001,642 a method is disclosed for the operation of a data processing system for motor vehicles including at least two computers and a line connecting the computers for the transmission of messages. An embodiment is provided which describes in detail the interface between the individual computers and the line linking the computers, and with the aid of which a controller-coupling is realized in the vehicle.
According to U.S. Pat. No. 5,675,830, a method and system is provided for assigning addresses to input/output (I/O) devices in a control network, and for verifying addresses assigned to the I/O devices. The system comprises a logic controller providing memory into which a connectivity map may be programmed. The connectivity map defines a specific expected address for each I/O device in the system. The logic controller further provides an external controller bus and logic for downloading the connectivity map to an I/O bus manager connected to the logic controller via the external controller bus. The I/O bus manager provides logic for assigning the specific addresses to the I/O devices. Network nodes connect the I/O bus manager to I/O cluster units in the system, each network node including a multiplexer for multiplexing output signals from the I/O bus manager and a demultiplexer for demultiplexing input signals from the I/O cluster units, the multiplexing/demultiplexing functions provided by a controller area network (CAN) integrated circuit. Each I/O cluster unit includes a multiplexer for multiplexing input signals from the I/O devices and a demultiplexer for demultiplexing output signals from its associated network node, the multiplexing/demultiplexing functions again provided by a controller area network (CAN) integrated circuit. Each I/O cluster unit provides means for manually requesting address assignments and a visual indication of addresses so assigned. Each I/O cluster unit also provides means to manually reject the address assigned to it by the I/O bus manager if the assigned address is not the expected address for the I/O cluster processor defined in the connectivity map.
None of above described documents provide for solutions according to the present invention.